"NR SBD Performance" calculation in Energy Pro

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No, the "NR SBD Performance" module does not use CBECC-Com. It used the standard EnergyPro DOE-2 engine. If you uncheck "delete temporary files after simulation is complete" in the calculations section, you can access the .bdl and .sim files to dive a bit deeper.

From my understanding, the "NR SBD Performance" module was created to follow the CPUC ruling that the SBD model must represent the actual performance of the proposed building. Therefore, this mode allows the user to specify schedules and plug loads and model system types not currently supported by CBECC-Com or the ACM.

The "standard" building is still created using Title 24 rulesets as in CBECC-Com, but follows the proposed building schedule and plug load inputs (and uses the DOE-2 engine, not EnergyPlus). The results are also still presented in TDV. I have not used this module extensively, or done a comparison between the two, but that amount of disparity sounds much too large. I would check any potential missing inputs, and review the .sim files (and add more reporting capability if necessary) to figure out what is wrong.

Here are a few things that I found for a building with VAV system

1). the zonal input for heating capacity is for reheat coil under compliance calculation (energy+);

but the .doe file in the SBD calculation shows the capacity is read as "baseboard" capacity, which was the case for previous version Energypro.

After I delete all heating capacity at the zonal system in the Design Case, the TDV heating energy consumption is reduced by 70%.

2). VAV turndown ratio must be higher than the min ventilation requirement and the min exhaust under compliance calculation (energy+); but the .doe and .sim file show the VAV turndown ratio for all zones are 0.2. After I changed all VAV turndown ratio to 0.2 in the Design Case, the TDV fan energy is reduced by 35%.

That's what I observed from test runs.